I think it depends if its been linked to your Steam account already, I've given away some Humble bundle keys via copying and pasting and sometimes it has worked, others not. I always use the gift option now.

You've missed some of the free Ubisoft Games over the last months?
No Problem, they're all free on Uplay till this Sunday.https://club.ubisoft.com/en-US/ubi30
That is:
Prince of Persia - The Sands of Time,
Splinter Cell,
Rayman Origins,
The Crew,
Beyond Good and Evil,
Far Cry Blood Dragon
and Assassin's Creed III

I recently got Elder Scrolls Anthology box from Poland of all places (15€ with shipping :D), just because I wanted the maps into my walls (They look epic BTW) :D

But I already have all the games (Well, Arena and Daggerfall can be gotten free if anyone wants to play those) but it came with a code that will supposedly give you English/Polish versions of Morrowind + Tribunal + Bloodmoon, Oblivion + Knights of the Nine + Shivering Isles and Skyrim (not Special edition) with all DLC. If anyone here wants to try out that code, PM me to get it.
Apparently, some of the people who ordered this same package couldn't activate that code for some reason, so I won't guarantee that you'll get the games, but nevertheless, I guess it wouldn't hurt to try it out :D

EDIT: Code already given away. But feel free to check my previous post for other games you can get instead... Maybe nothing as glamorous as this, but perhaps something else worthwhile :)